Bis(pyrazolato)-Based Metal–Organic Frameworks Fabricated with 4,4′-Bis((3,5-dimethyl‑1<i>H</i>‑pyrazol-4-yl)methyl)biphenyl and Late Transition Metals

The reaction between the flexible, bis­(pyrazolato)-based ligand 4,4′-bis­((3,5-dimethyl-1H-pyrazol-4-yl)­methyl)­biphenyl (H2DMPMB) and late transition metal ions allowed the isolation of the two series of thermally stable metal–organic frameworks [M­(DMPMB)] (M = Co, Zn, Cd) and [M2(DMPMB)] (M = Cu, Ag). X-ray powder diffraction (XRPD) structure determinations demonstrated that the anti conformation adopted by the ligand, juxtaposed to its exo-tetradentate coordination mode, induces the formation of a 3-D architecture with nonpervious 1-D channels in the three isomorphous species [M­(DMPMB)] and of corrugated 2-D layers in [Cu2(DMPMB)]. Coupling thermogravimetric analyses and variable temperature XRPD highlighted that the five materials are thermally stable at least up to 300 °C, both under nitrogen and in air, the Cd­(II) derivative decomposing only at the remarkably high temperature of 500 °C. No thermal event could be detected; all the materials preserve their structural motifs up to decomposition. The adsorption properties of the five compounds were assayed toward N2 at 77 K: while no adsorption was observed for [Cd­(DMPMB)], the other species possess estimated BET and Langmuir specific surface areas in the ranges 64(1)–526(3) m2/g and 142(4)–713(27) m2/g, respectively, thus being an example of the interesting phenomenon known as “porosity without pores”. Finally, the luminescence properties of the Zn­(II), Cd­(II), and Cu­(I) derivatives were investigated.柔性双(吡唑根)类配体4,4′-双((3,5-二甲基-1H-吡唑-4-基)甲基)联苯（H₂DMPMB）与后过渡金属离子发生反应，成功分离得到两个系列的热稳定金属有机框架材料：[M(DMPMB)]（M = Co、Zn、Cd）与[M₂(DMPMB)]（M = Cu、Ag）。X射线粉末衍射（XRPD）结构解析结果显示，该配体采取反式构象并结合其外向四齿配位模式，诱导同构的[M(DMPMB)]系列三种材料形成带有非贯通一维孔道的三维网状结构；而[Cu₂(DMPMB)]则形成波纹状二维层状结构。结合热重分析与变温XRPD测试结果可知，五种材料在氮气与空气氛围下均至少可稳定至300 ℃，其中镉(II)衍生物甚至在高达500 ℃的温度下才发生分解。未观测到其他热转变事件，所有材料在分解前均能完整保留其结构基元。对五种化合物在77 K下的氮气吸附性能进行了测试：[Cd(DMPMB)]未表现出明显吸附行为，其余物种的BET与Langmuir比表面积分别处于64(1)–526(3) m²/g与142(4)–713(27) m²/g的范围内，因此这类材料属于被称为‘无孔孔隙性（porosity without pores）’的有趣现象的实例。最后，对锌(II)、镉(II)与铜(I)衍生物的发光性能开展了研究。